Question

A 10.0 g object moving to the right at 17.0 cm/s makes an elastic head-on collision with a 15.0 g object moving in the opposite direction at 35.0 cm/s. Find the velocity of each object after the collision.

10g object

15g object

Answer 1

in every type of collision momentum is conserved

so in an elastic collision

velocity of approach=velocity of separation

17cm/s-(-35cm/s)=v-u.........1)

u=final velocity of 10 g object

v= final velocity of 15 g object.

from equation 1

v=u+52cm/s.........2)

from conservation of momentum we have,

10g*17cm/s-15g*35cm/s=10g*u+15g*v

substituting the value of v

170-525=10u+15(u+52)

-355=10u+15u+780

25u=-1135

u=-45.4cm/s

from equation 2

v=-45.4cm/s+52cm/s=6.6cm/s

so after collision the velocity of 10g object= -45.4cm/s or -45 cm/s

and velocity of 15 g object=6.6cm/s or 7cm/s